Fetal Cardiac Care

by Dr Mridul Agarwal

Fetal Doppler PI & RI Calculator: Umbilical, MCA & Ductus Venosus Centiles

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Dr. Mridul Agarwal, MD, FNB (Pediatric Cardiology)
Senior Consultant, Pediatric & Fetal Cardiac Sciences | Sir Ganga Ram Hospital, New Delhi
Reference Standards: ISUOG & Arduini-Rizzo Centiles
Vascular Beds: UA, MCA, DV, and CPR Ratio

📈 Interactive Fetal Doppler PI/RI Centile Tool

Centile Calculation Engine

Select gestational age and enter Pulsatility Index (PI) or Resistive Index (RI) to obtain instant gestational centiles and cerebroplacental ratio (CPR) quantification.

Vascular Bed Interpretation Framework

1. Umbilical Artery (UA PI)

Reflects placental villous vascular resistance. Normal PI declines smoothly with advancing gestation. Elevated PI (>95th centile), Absent (ARED), or Reversed End-Diastolic flow indicates placental insufficiency.

2. Middle Cerebral Artery (MCA PI)

Low impedance (<5th centile) indicates “brain-sparing reflex” where the fetus vasodilates cerebral vasculature in response to chronic hypoxia.

3. Ductus Venosus (DV PI)

Reflects right ventricular compliance and right atrial filling pressure. Absent or reversed a-wave is an ominous marker of cardiac decompensation.

4. Cerebroplacental Ratio (CPR)

CPR = MCA PI / UA PI. A ratio < 1.0 or <5th centile is more sensitive than either vessel alone for predicting adverse perinatal outcomes.